Not Applicable.
1. Field of the Invention
The present invention relates to training and rehabilitating brain function, and in particular, to the use of occluded contact lenses with peripheral vision functionality to accomplish this purpose.
Brain injury, such as Cerebral Vascular Accident (stroke), closed head injury, penetrating head wounds, and invasive growths can generate a variety of sensory/perceptual and other cognitive disturbances that significantly impact the ability of individuals to maintain independence in their environments. When this insult occurs in the posterior regions of the brain, especially the parietal and/or occipital lobes, a change in the functioning of the visual perceptual system can occur. These sensory/perceptual disturbances involve inattention to visual stimuli to a varying degree, from mild inattention to details to complete loss of recognition of visual information in a given visual field. In some instances, perception of the visual field disappears completely.
There are few options for rehabilitation of the patient with a visual perceptual defect. Most techniques involve behavioral and/or cognitive training directed at focused extra attention to the visual field that has been disrupted. The results of this type of rehabilitation have been successful, but limited.
Recent evidence showing that attention plays an essential role in almost all other brain functions including motor functioning in stroke patients with hemiparesis or hemiplegia suggests that any technique that can improve attention related to brain injury might help in the recovery of many non-vision related brain functions. In addition, some research has established a relationship between hemispheric attention and visual processing in the dysfunction of developmental reading disorder, the most common type of learning disability.
Furthermore such improvement in brain function could also be effective in visual training in non-medical settings. For example, baseball batters use asymmetric visual information when standing at the plate judging pitches. Isolating the field that captures the pitcher and pitch, and blocks the catcher, umpire, and other distractions might significantly improve batting performance.
2. Brief Description of the Related Art
Contact lens, glasses and the like are known in which regions of the lens are rendered opaque or semi-opaque for the purpose of correcting defects in vision or to shield the eye from damage. A lens in which regions of the lens are opaque or semi-opaque are referred to herein as an occluded lens.
Harrell, E. H., T. Kramer-Stutts, and A. J. Zolten, xe2x80x9cPerformance of Subjects with Left Visual Neglect after Removal of the Right Visual Field Using Hemifield Goggles,xe2x80x9d Journal of Rehabilitation, (October/November/December 1995), pp. 46-49, discloses improved performance with visual input directed to a neglected field when the non-neglected field is occluded. Harrell et al. disclose complete occlusion of the visual field directed to one hemisphere of the brain. Harrell et al. disclose changing the amount of visual field input by adjusting Velcro strips on goggles to provide occlusion.
While Harrell et al. suggest that in the future a procedure using contact lenses might be preferable to goggles, they conclude that this would be expensive and probably not feasible for practical applications in rehabilitation. However, various techniques are known for manufacturing contact lenses with opaque or tinted areas.
One of the problems in using contact lens having occluded regions is that the contact lens must sit on the eye without rotation. Various techniques are known for maintaining the position of a contact lens without rotation. For example, such techniques are disclosed in U.S. Pat. Nos. 4,324,461; 5,483,304; 5,502,518; and 5,570,142.
Lofgren-Nisser in U.S. Pat. Nos. 6,062,687 and 5,570,144 discloses a contact lens with a vertical orienting mass and an occluded portion that restricts light passing through the occluded portion.
The present invention is an occluded contact lens which selectively blocks visual sensory input to a specific portion of the brain.
The xe2x80x9cblindingxe2x80x9d of the sensory-blocked portion of the brain forces processing of all primary visual information to the remaining portions of the brain. This technique is useful in the rehabilitation of visual field defects, training of brain function and for other purposes.
For example, if the left halves of each of a pair of contact lenses are rendered opaque (e.g., by patching the left half of each lens with black non-translucent contact lens plastic), visual processing is forced to the left hemisphere of the brain thereby stimulating that area of the brain. Occluding the right halves of each of a pair of contact lenses with opaque material would stimulate the opposite hemisphere.
Specific areas of the brain are targeted by selectively blinding portions of each of a pair of contact lenses over more or less than a full hemisphere. For example, a particular quarter segment of each lens could be rendered clear or the remaining xc2xe segment could be rendered opaque. Various combinations of blocked portions of the contact lenses may therefore be utilized to force visual processing to a particular portion of the brain that is thereby stimulated. Each contact lens is weighted or otherwise constructed so that the lenses sit on the eye without rotating.
A method of using the occluded contact lens to rehabilitate a patient with a visual defect or training specific visual processing areas consists of having the patient perform visual and non-visual tasks constructed to activate processing in the targeted portion of the brain. A graduated series of occluded contacts lenses constructed of semi-transparent material of varying degrees of opacity may allow the patient""s visual system to adapt in stages to the rehabilitated balance between intact visual processing and releamed visual processing.
One difficulty in having the patient perform tasks with a portion of the visual field occluded, particularly tasks that involve motion of the patient, is that occlusion of a significant portion of the visual field of one or both hemispheres may leave the patient without the means for orientation and balance, since a significant proportion of the sensory input from which the brain derives orientation cues is visual. It is therefore desirable to leave portions of the visual field un-occluded for visual orientation cues. However, this works against the desirability of completing excluding visual information from the non-targeted areas of the brain. The solution of the present invention is based on the principle that the visual field is not uniform in regard to the quantity of visual information received and processed. The central visual field, i.e., the portion of the visual field within a relatively narrow cone with an axis aligned with the line along which the eye is fixed (xe2x80x9cthe central visual axisxe2x80x9d), processes a much greater amount of information than the portions of the visual field farther from the central visual axis. The latter portions of the visual field, the peripheral visual field, therefore do not contribute a significant amount of visual information to the brain. The peripheral visual field, however, does significantly factor into the establishment of balance and orientation cues.
The present invention therefore uses these principals to maintain a significant degree of occlusion of visual information being received by non-targeted areas of the brain while allowing information from the peripheral visual field to be received by the non-targeted areas of the brain in order to preserve sufficient visual cues for orientation and balance. This is accomplished by dividing each contact lens into three regions: a first region is substantially clear over the portion of the pupil of the eye directing visual information to the targeted area of the brain, a second region is occluded over substantially all of the portion of the pupil of the eye directing visual information to the non-targeted area of the brain, and the third region is substantially clear over at least a portion of the peripheral visual field corresponding to the non-targeted area of the brain to allow for visual cues sufficient for balance and orientation of the patient.
It is therefore an object of the present invention to provide for a contact lens product having occluded regions to force visual processing to targeted areas of the brain to encourage rehabilitation and training of such targeted areas while maintaining sufficient visual cues from the peripheral visual field to allow the patient to maintain balance and orientation.